If you check your 2010 Census form, "Chicano" appears as an option for people of Hispanic, Latino, or Spanish origin. But it's not the first choice; "Mexican" and "Mexican Am." precede it. Even in the context of "Phantom Sightings: Art After the Chicano Movement," at El Museo del Barrio, the term often gets tossed aside. One event advertised its speaker as a "post-Mexican." Wall labels and the catalog freely admit that many of the artists in the show don't identify as Chicano, that it's just a "curatorial point of departure."

So why mount a "Chicano" exhibition? One answer: It gives the Chicano Studies Research Center at UCLA, which partnered with the Los Angeles County Museum of Art to create the show, another raison d'être. It also demonstrates how younger artists' focus has shifted away from language and into the real world, toward borders and space and what has resulted from trying to police these quasi-arbitrary entities.

"Phantom Sightings" is a wildly uneven show. It's also seriously lacking in didactics (i.e., wall texts) that would close a few gaps in understanding. The title, though, is useful. It comes from Harry Gamboa Jr., an artist who described Chicanos in the '70s as a "phantom culture" within the United States.

In Delilah Montoya's panoramic photographs of U.S.-Mexican border-crossing zones, Migrant Campsite, Ironwood, AZ (2004) and Powerline Trail, Ironwood, AZ (2004), no humans are present—only traces in the form of discarded clothes, water bottles, and backpacks. Move to the left or right while looking at Ruben Ochoa's lenticular photographs What if walls created spaces? (2006) and concrete walls vanish and a dry, grassy hill appears.

Julio César Morales's Undocumented Interventions (2005–2008) similarly pivot around absence, presence, and a kind of magical-thinking invisibility. Watercolor drawings show cut-away images of people nestled inside a washing machine, embedded in airplane seats, or in the dashboard of a car. A video switching between border footage and digitized animation turns the ugly concrete divider into a Rorschach-y psychedelic hallucination.

Historical documentation can be phantom fodder, as well. Ken Gonzales-Day takes familiar lynching images and re-photographs them, erasing bodies hanging from trees and telephone poles to create eerie voids within the pictures. W.H. Horne's grainy photo from 1916 of U.S. General John J. Pershing's troops "Executing Bandits in Mexico" from Pancho Villa's ranks—that text is handwritten on the vintage print—revises the photo, removing the "bandit."

One of the most unassuming and interesting works in the show is Arturo Ernesto Romo's rough split-screen video in which he attempts to track down urban Chicano wall murals. What he discovers is a kind of disappeared art history: The murals, on the sides of humble low-rise buildings in Los Angeles, have been painted over with plain, flat color. This has a special resonance in New York, where legendary Mexican muralist Diego Rivera's fresco in a Rockefeller Center building lobby was destroyed in 1933 after he refused to remove a portrait of Lenin leading a May Day parade.

Two other works worth mentioning, both by Carlee Fernandez, deal more with identity, that '90s catchword. But what's not to love about her "Self-Portraits," in which she licks a blown-up photo of Lars von Trier, or holds up head shots of Werner Herzog, Franz West, or Megadeth frontman Dave Mustaine in front of her own face? Fernandez's communing with patriarchy gets even more personal in a diptych re-creating a portrait of her father, down to the clothing, pose, and sunlit/tall-grass setting. It's a little like Gillian Wearing's creepy family-photo remakes, except with Chicana nuances (minus only that signifier of Latino masculinity: the mustache).

Elsewhere, traditional Mexican ceramics, textiles, and folk paintings are treated as readymade source material for contemporary art. This line of inquiry into culture, history, identity—whatever you want to cite—isn't very strong. It's the photography and video in "Phantom Sightings" that deliver the greatest impact. This makes sense, since these media work best at creating phantoms, in slipping between history and the present, material and immaterial, this state and that one. When you're talking about porous borders, invisible immigrants, and shifting identity politics, this seems about as concrete as it gets—an appropriate way of representing the undocumentable.